Experiments on neoclassical tearing mode stabilization by ECCD in ASDEX Upgrade

The reduction of neoclassical tearing modes by ECCD is demonstrated experimentally. It is shown that with an averagedECCD power of only 4-8% of the total heating power injected into the discharge, the island width can be reduced by40%, provided that the centre of deposition is very close to the resonant surface.The reduction in mode amplitude results in a partial recovery of the loss of stored energy induced by the mode. This experimental result is well reproduced by modelling calculations.